Language design

[vyorkin]

moved from shitjs/meta/issues/2

Initial thoughts

informal description

0. written in JavaScript
1. no statements, only expressions
2. no var (variables are always declared in a global scope by default)
3. no return – ShitScript returns the last evaluated expression
4. no floating point numbers (only integers)
5. no unary operators (?)
6. no classes, no array's, no object's (except for console and window)

shitty ideas

• allow using -, ?, ! in function names (no-camel-case)
• super weird type coercions (or just some non-obvious implicit coercions result in string 'shit')
• ; -> )))
• === -> ====, !== -> !===
• (...) -> [...]
• function -> shit / fuck
• try -> why-the-fuck-not
• catch -> fucked-up
• finally -> dont-fucking-care
• say please to enable lexical scoping
• you can't use a couple of numbers (e.g. 4 and 2) for no reason
• x / 0 = Math.random()
• if -> o-rly?
• then -> ya-rly
• else -> no-way
• o-rly?-ya-rly-no-way for one-liners (without brackets)
• . -> -> (works only for console and window)

an example program:

fuck wat[] {
 calculate!!![2, 0])))
}

shit calculate!!![y, x] please {
 z = 5)))
 why-the-fuck-not {
 o-rly? z % 2 ==== 0 {
 y / x)))
 } no-way {
 x / y)))
 }
 } fucked-up[e] {
 console.lol[e])))
 } dont-fucking-care {
 0)))
 }
}

P.S.: Not sure about using words fuck and shit everywhere (may be considered offensive)

[ghaiklor]

What ideas do you have comrades, for parser\tokens\etc ? Are we gonna to use some existing tools for writing our alphabet, lexical\semantic rules and so on ?

i.e. we can use Jison for parser.

[vyorkin]

looks interesting, @ghaiklor, haven't seen it before, will definitely play with it tonight.
recently I had an experience with pegjs and I believe I know how to write LL(k) parser from scratch (I'm reading Language Implementation Patters by Terence Parr book), but yes, I think its better/easier to use existing tools (DSL + parser generator) for describing our shitty formal grammar and Jison looks promising from the first sight.

[chicoxyzzy]

function -> shit

I like this particularly because we can have some sort of a higher order shit

[vyorkin]

ok, sorry for not doing anything for quite a while, I'll get back to it very soon, I hope!

[ghaiklor]

@vyorkin played a little bit with LLVM... What if we will take LLVM as a compiler and write LLVM frontend for our ShitScript ?

[vyorkin]

@ghaiklor good idea (I've just watched this talk https://www.youtube.com/watch?v=PauCAyVg348), I need to build smth very simple first (sorry still don't have enough time)

[chicoxyzzy]

we definitely should target LLVM so we'll be able to use emascripten to target wasm

[chicoxyzzy]

oops

[ghaiklor]

@vyorkin here is my playground for llvm, but nothing special - https://github.com/ghaiklor/llvm-kaleidoscope

[vyorkin]

how about using Rust + llvm-rs + lalrpop to build this? I'm going to start working on it these weekends, the time has come :)
my plan:
– build a very basic formal grammar
– generate a parser with lalrpop (we'll need to write a custom lexer & parser later for performance reasons), but it'll suffice for now
– write some tests to verify the resulting AST
– implement a visitor that will walk the AST and generate some LLVM IR
– provide a very basic REPL (to ease testing & playing with it) that will accept options like:

 -a, --ast Parse and output AST
 -i, --llvm-ir Build and output LLVM IR

we could use docopt or clap crates for CLI args parsing

I'm still learning & playing with llvm-rs crate (the Compile module is complex, a lot of macroses & metaprogramming stuff), but there aren't many alternatives, I've seen them all and llvm-rs seems to be the most mature, but its not under active development

[ghaiklor]

@vyorkin I've started R&D in parsers written in JavaScript. Found goodpossible solutions we can use.

Lexical analysis - Jalex. You can describe rules via regular expressions and it will call a callback when match is found. So, we will be able to describe lexical rules via regular expressions and implement all needed actions for returning a stream of tokens.

Semantic analysis - Jison. It has its own simple built-in lexical analyzer, though, I'm thinking to use Jalex, since we will definitely write our own scanner in future.

Why I chose them? They are compatible with lex\yacc format. So you can describe definitions, translation rules in plain old-way as it was done in yacc.

For a grammar, we can try to found already implemented grammar for JavaScript and just modify it to fit our needs.

Though, still thinking about other lexical analyzers, but for semantic analysis I didn't found too much, so seems like Jison is our only options for semantic.

[vyorkin]

@ghaiklor do you know any good LLVM bindings for nodejs? I've found only these 2:

• https://github.com/dirk/llvm2
• https://github.com/kevinmehall/node-llvm
  both seem outdated :(
  LLVM is hard, but I've already wasted so much time learning it, I think its too late to give up on it :)